fifth, we need new technology. we are seeing cameras and local communities, sensors. we will probably seek a fierce debate in the united states about commercial drones and how active those can be, and trying to make sure civil liberties and protections for our civil liberties and civil rights are set up so that we can use them or may not be able to use them. >> that, of course, is always a balance. what is the time frame you are looking at now? >> 50 forensics is under way. the search for seized -- the forensics is under way. the search for cc tv is under way. it could take a long, long time, especially if someone has made it out of the country or has been very careful in how they have done this. it is very open-ended and very difficult to predict. >> and no one has claimed responsibility. i'm afraid i will have to leave it there. thank you for coming in. there will be more than 30 marathons around the world next weekend, and the events in boston have implications globally. insiston, organizers that the marathon will go ahead, but with a massive 36,000 runners and hal